At a time when treatment of the fetus has become feasible, it is essential to be able to estimate the severity of stress in utero. Cardiac function is known to be an indicator of general well-being. Non-invasive methods have been used to assess cardiac function in neonates, children and adults; and we expect that they will be useful in evaluating stress in the fetus. We propose to evaluate cardiac function in utero by means of echocardiographic records of valve motion and fetal electrocardiograms. Fetal Systolic Time Intervals (STI), Circumferential Fiber Shortening Rate (mVCF) and Chamber Diameters will be measured serially in a group of normal fetuses followed from 24 weeks gestation through the newborn period and in several groups suffering from well-defined fetal distress syndromes. Recent reports of studies in exteriorized animal fetuses and in human fetuses during delivery have led us to expect stress related changes in systolic time intervals in utero. We have shown in our preliminary studies that it is feasible to measure the above parameters in the fetus. Simultaneous recordings of fetal phonocardiograms and Doppler signals associated with valve motion may aid in verifying these methods and in developing fetal monitors by automated analysis of fetal STI. It is our hope that changes in systolic time intervals will allow early identification of fetuses at risk for decompensation so that deliberate plans of treatment can be instituted.